Finish Decompiler

[ssanderson]

Currently Handles:

• [x] For-Loops
• [x] While-Loops
• [x] All Binary Operators except or and and.
• [x] Dict/Set/Tuple/Number/String/Name Constants
• [x] Function Definitions
• [x] Chained Assignments
• [x] Unpacking Assignments
• [x] With-Blocks
• [x] Global and Nonlocal Declarations
• [x] Imports

Does Not Currently Handle:

• [ ] Python != 3.4.3
• [x] If-Statements
• [x] or and and
• [x] ternary expressions
• [ ] Class Definitions
• [ ] Comprehensions
• [x] Lambdas
• [ ] Try-Except-Finally Blocks
• [ ] Raise Statements
• [ ] Assert Statements
• [ ] Comparisons

[llllllllll]

There is an issue with if statements:

In [5]: def f():
   ...:     if a:
   ...:         return 1
   ...:     else:
   ...:         return 2
   ...:     

In [6]: dis(f)
  2           0 LOAD_GLOBAL              0 (a)
              3 POP_JUMP_IF_FALSE       10

  3           6 LOAD_CONST               1 (1)
              9 RETURN_VALUE

  5     >>   10 LOAD_CONST               2 (2)
             13 RETURN_VALUE
             14 LOAD_CONST               0 (None)
             17 RETURN_VALUE

This currently raises: DecompilationError: Expected a JUMP_FORWARD instruction at end of if-block. Got RETURN_VALUE.

This makes finding the end of an else really hard/impossible; however, I think we can totally get rid of the else if the if ends in a return. This code ends up being the same as:

def f():
    if a:
        return 1
    return 2

[Carreau]

Adding on top of that : Python 3.6 has no CALL_FUNCTION_VAR anymore.

[llllllllll]

Right now we are just trying to finish the 3.4.3 decompiler, when we get that mostly complete we will work on expanding to 3.5 and 3.6